Field of the Invention
The present invention relates in general to phototherapy, and more particularly, to novel apparatuses and methods for phototherapy of brain tissue.
Description of the Related Art
There are numerous neurologic conditions, such as neurodegenerative diseases (e.g., Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis), Huntington's disease, demyelinating diseases (e.g., multiple sclerosis), cranial nerve palsies, traumatic brain injury, stroke, depression, and spinal cord injury which could possibly benefit from application of phototherapy. Most of these conditions cause significant morbidity and mortality and involve tremendous burden to society, families and caregivers. Many neurologic conditions have no currently available effective therapies or the therapies that are available are not adequate to restore functional recovery, sustain quality of life, or halt disease progression.
One example of a neurologic condition that remains a major unmet medical need is stroke, also called cerebrovascular accident (CVA). Stroke is caused by a sudden disruption of blood flow to a discrete area of the brain that is brought on by the lodging of a clot in an artery supplying blood to an area of the brain (called an ischemic stroke), or by a cerebral hemorrhage due to a ruptured aneurysm or a burst artery (called a hemorrhagic stroke). There are over 750.000 stroke victims per year in the United States, and approximately 85% of all strokes are ischemic and 15% are hemorrhagic. The consequence of stroke is a loss of function in the affected brain region and concomitant loss of bodily function in areas of the body controlled by the affected brain region. Depending upon the extent and location of the primary insult in the brain, loss of function varies greatly from mild or severe, and may be temporary or permanent. Lifestyle factors such as smoking, diet, level of physical activity and high cholesterol increase the risk of stroke, and thus stroke is a major cause of human suffering in developed nations. Stroke is the third leading cause of death in most developed nations, including the United States.
Stroke treatment is often restricted to providing basic life support at the time of the stroke, followed by rehabilitation. Currently, the only FDA-cleared treatment of ischemic stroke involves thrombolytic therapy using tissue plasminogen activator (tPA). However, tPA can only be used within three hours of stroke onset and has several contraindications, therefore, only a small percentage of stroke victims receive this drug.
Traumatic brain injury (TBI) occurs when a sudden physical trauma (e.g., crush or compression injury in the central nervous system, including a crush or compression injury of the brain, spinal cord, nerves or retina, or any acute injury or insult producing cell death) causes damage to the head. For example, a sudden and/or violent blow to the head or an object piercing the skull and entering brain tissue can result in TBI. The extent of damage to the brain can be severe, however even mild and moderate TBI has been associated with neurological sequelae that can be long lasting. Development of neurodegenerative conditions has been associated with TBI. TBI can result in a sudden disruption of blood flow to a discrete area of the brain. The consequence of stroke or TBI can be a loss of function in the affected brain region and concomitant loss of bodily function in areas of the body controlled by the affected brain region. Depending upon the extent and location of the primary insult in the brain, loss of function varies greatly from mild or severe, and may be temporary or permanent.
A high level of interest and clinical need remains in finding new and improved therapeutic interventions for treatment of stroke and other neurologic conditions that continue to devastate millions of lives each year and where few effective therapies exist.